From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753087AbcHOQLm (ORCPT ); Mon, 15 Aug 2016 12:11:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50142 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752801AbcHOQLG (ORCPT ); Mon, 15 Aug 2016 12:11:06 -0400 From: Vitaly Kuznetsov To: KY Srinivasan Cc: "devel\@linuxdriverproject.org" , "linux-kernel\@vger.kernel.org" , Haiyang Zhang Subject: Re: [PATCH 0/2] Drivers: hv: vmbus: make bus ids in sysfs persistent References: <1470732379-5013-1-git-send-email-vkuznets@redhat.com> <87twer8y2w.fsf@vitty.brq.redhat.com> Date: Mon, 15 Aug 2016 18:11:03 +0200 In-Reply-To: (KY Srinivasan's message of "Fri, 12 Aug 2016 14:10:05 +0000") Message-ID: <87lgzyau7c.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.95 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 15 Aug 2016 16:11:05 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KY Srinivasan writes: >> -----Original Message----- >> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com] >> Sent: Thursday, August 11, 2016 2:17 AM >> To: KY Srinivasan >> Cc: devel@linuxdriverproject.org; linux-kernel@vger.kernel.org; Haiyang Zhang >> >> Subject: Re: [PATCH 0/2] Drivers: hv: vmbus: make bus ids in sysfs persistent >> >> KY Srinivasan writes: >> >> >> -----Original Message----- >> >> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com] >> >> Sent: Tuesday, August 9, 2016 1:46 AM >> >> To: devel@linuxdriverproject.org >> >> Cc: linux-kernel@vger.kernel.org; Haiyang Zhang >> >> ; KY Srinivasan >> >> Subject: [PATCH 0/2] Drivers: hv: vmbus: make bus ids in sysfs >> >> persistent >> >> >> >> Bus ids for VMBus devices in /sys/bus/vmbus/devices/ are not >> >> guaranteed to be persistent across reboot or kernel restart and this >> >> causes problems for some tools. E.g. kexec tools use these ids to identify >> NIC on kdump. >> >> Fix the issue by using relid from channel offer as the unique id >> >> instead of an auto incremented counter. >> > >> > Relids are not persistent. It is only valid between a channel offer >> > message and a relid released message (or an unload or initiate contact >> > message, which invalidates all channels). This is an opaque number >> > that the root generates and uses to track channels. There is no >> > guarantee that the same type of channel (networking, storage, etc) >> > will get the same relid on each reboot. >> > >> >> Thanks for the info, >> >> can we use device_id (offermsg.offer.if_instance.b) instead? > > I think you could; I am going to verify and get back to you on this. Thanks! > Sometime back I removed all the non-determinism in the vmbus device > ID generation. Now, the current scheme of generating the device IDs does > result in persistent IDs across boot (as long as the host presents the devices > to the guest in the same order across boots). Do you have this fix? Yes, I think I do. The issue I'm trying to address happens rearly on kdump when we get devices present to us in a different order. -- Vitaly